CVE-2026-4286
Mattermost Team ID Change Bypass in Playbooks
Publication date: 2026-05-18
Last updated on: 2026-05-18
Assigner: Mattermost, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mattermost | mattermost_server | From 10.11.0 (inc) to 10.11.14 (exc) |
| mattermost | mattermost_server | From 11.5.0 (inc) to 11.5.2 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-863 | The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability affects Mattermost versions 11.5.x up to 11.5.1 and 10.11.x up to 10.11.13. It occurs because the software fails to verify whether the {{team_id}} field is being changed when updating playbooks. As a result, users who have only the Manage Playbook Configurations permission can change a playbook's associated team. This bypasses the intended restriction on managing members via the PUT API.
How can this vulnerability impact me? :
The impact of this vulnerability is that users with limited permissions (specifically, only Manage Playbook Configurations) can change the team associated with a playbook. This allows them to bypass restrictions that normally prevent them from managing members of that team, potentially leading to unauthorized changes in team configurations or access.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should update Mattermost to a version later than 11.5.1 for the 11.5.x branch or later than 10.11.13 for the 10.11.x branch, where the issue has been fixed.
Additionally, review and restrict permissions related to managing playbook configurations to trusted users only, as the vulnerability allows users with Manage Playbook Configurations permission to bypass manage members restrictions.